Cell allocation to the inner cell mass and the trophectoderm in bovine embryos cultured in two different media

A Shorter Equilibration Period Improves Post-Warming Outcomes after Vitrification and in Straw Dilution of In Vitro-Produced Bovine Embryos

“…However, while it is accepted that a minimal number of embryonic cells is needed to establish pregnancy [33], optimal ICM and TE cell numbers and distributions in the blastocyst remain unclear. Thus, higher ICM cell counts may lead to increased pregnancy rates [34], and an excessive number of cells allocated to the TE may lead to pregnancy abnormalities [35,36]. Here, the TUNEL assay combined with differential staining for ICM and TE cells revealed significantly lower TCN and TE cell numbers and a higher apoptosis rate in vitrified/warmed D7 re-expanded blastocysts compared to fresh ones, while no differences emerged in ICM cell numbers, suggesting that the main site of cryopreservation-related membrane damage was the trophectoderm.…”

“…However, among the D8 embryos subjected to vitrification/warming, TCN, ICM, and TE cell numbers were significantly lower in hatching blastocysts when compared to fresh blastocysts, regardless of the equilibration time. The timing of blastocyst formation is a good marker of embryo quality, with early-cavitating embryos being of better quality than later cavitating embryos in terms of total cell numbers, inner cell mass and trophectoderm cell distributions, and cryosurvival [35,39]. While we still lack reliable blastocyst stage morphological predictors of competence after embryo transfer, it is accepted by many research groups and commercial companies that best pregnancy rates are achieved after the transfer of D7 expanded bovine blastocysts, whether fresh or cryopreserved (reviewed by [42,43]).…”

127 Development and Quality of Bovine Morulae Cultured in Serum-Free Medium With Retinoic Receptor Specific Agonists

“…Iwasaki et al (1990) found that IVP embryos had a lower ratio of ICM to TE cells, and a less compact ICM compared with both embryos produced entirely in vivo and embryos matured and fertilised in vivo but cultured in vitro. A minimum number of ICM cells is required to obtain a pregnancy and excessive allocation of cells to the TE may lead to pregnancy abnormalities (Van Soom et al 1996;Leese et al 1998). In a previous study, culture of morulae with 0.7 µm ATRA increased ICM and TE cell numbers in the presence of serum (Rodríguez et al 2006).…”

Treatment of Buffalo ( Bubalus bubalis ) Somatic Cell Nuclear Transfer Embryos with MicroRNA-29b Mimic Improves Their Quality, Reduces DNA Methylation, and Changes Gene Expression Without Affecting Their Developmental Competence

“…Mammalian blastocysts are composed of the ICM, which forms the embryo, and the TE, which forms the extraembryonic tissues of the placenta. An appropriate ratio of cell numbers between ICM and TE is necessary for normal embryonic development and is employed for assessing the quality of blastocysts (Van Soom et al, 1996; Yu et al, 2007).…”